At the massive MarkWest processing plant near Evans City, Action News Investigates found workers driving cars from Texas, Wyoming, Kentucky, Georgia and many other states. Some of them went to area hotels. Only a handful of cars were from Pennsylvania.

“That gas below us belongs to Pennsylvanians. And Pennsylvanians should be the people that benefit from that gas,” he said.

Costa, D-Pittsburgh, sent a letter to MarkWest, urging them to hire more local workers.

Similar letters were also sent by legislative caucuses from Southwest and Northwest Pennsylvania.

"This is about Pennsylvanians," Costa said. "It isn't about union, non-union. It's about putting our people to work."

In a statement, MarkWest said in the past two years 75 percent of its major area projects have gone to union contractors resulting in 1,500 union jobs.

"Any suggestion that MarkWest does not utilize local union labor is verifiably false and fully unsupported by the facts," the company said.

Some legislators are also concerned that some workers at the processing plant may be in this country illegally. When Rep. Jim Marshall toured the site, he noticed many of the workers were speaking Spanish.

"I didn't see a lot of Don Jones and Sam Smith names on the helmets. I was just concerned how broad an area they're drawing from,” said Marshall, R-Beaver County.

“We need to make sure that the job is, number 1, safe, and number 2, everybody on the job is here legally,” said Costa.

MarkWest did not directly respond to the legislators' concerns that some of the workers might be here illegally.

Costa said he plans to co-sponsor a bill with Rep. Daryl Metcalfe, R-Butler County, that would require all Pennsylvania companies to verify their workers are here legally.

Costa and Marshall also want to create tax incentives for the gas industry to hire more Pennsylvania workers.